In turbofan engines, differences in the fan material versus fan case material may contribute to thermally-induced rub. The fan blades are subject to radial expansion due to inertial forces associated with fan rotation (centrifugal loading). The fan blades are also subject to thermal expansion which is influenced by the material properties of the fan blades (e.g., the coefficient of thermal expansion (CTE)). The fan case is also subject to thermal expansion. In operation, there typically is a gap or clearance between the fan blade tips and the adjacent inboard surface portion of the fan case. On the one hand, it is desirable to keep this gap small to maintain engine efficiency. On the other hand, it is generally desirable to avoid having this gap fully close which produces rub.
The fan case includes a structural member/case comprising a containment case. The containment case may be formed as a composite (e.g., carbon fiber and epoxy resin) to maintain as light a weight as possible. Within the containment case is fitted a replaceable liner cartridge that includes an abradable rub material that will be harmlessly abraded if the fan blade tips contact the abradable rub material. The containment case includes a ballistic liner formed from aramid fiber laminate co-cured to the inner surface of the carbon composite containment case. The ballistic liner is designed to blunt any unplanned blade impact events due to release or partial release of a fan blade.